1. Technical Field
This invention relates to an unloading shoe subassembly for use in combination with a hand truck and, more particularly, to an unloading shoe subassembly for use with a wheeled hand truck which includes a pair of wheeled track assemblies each including three tracks and wheels slidably mounted within each of the tracks, a shoe assembly including a shoe and at least one shoe support strut, and a handle including a pair of sideframe members, the sideframe members pivotably connected to the wheel in the upper track and also to the shoe support strut, the shoe support strut pivotably connected to the wheels in the middle and lower tracks whereby the shoe support strut is tilted to move the shoe generally parallel with the load-carrying platform of a hand truck.
2. Description of the Prior Art
The use of hand trucks for moving relatively small but heavy objects from one place to another is a generally common practice. For example, delivery companies such as United Parcel Service or Federal Express supply hand trucks to their delivery people to facilitate the transport of materials from one location to another. Also, furniture and appliance movers commonly use the 2-wheeled hand truck for transporting any items to be moved.
A typical hand truck would include the following features: an upright frame commonly including a pair of upright frame members, a generally horizontal load-carrying platform mounted at the lower end of the frame and a pair of wheels attached to the frame by an axle. The hand truck may also include a handle for simplifying transport of the hand truck.
Parcels are removed from the hand truck by tilting the load-carrying platform forwards and sliding the platform from underneath the parcels. There are several disadvantages to this method of removing packages from the platform, including that the packages must be tilted to be removed from the load-carrying platform, which may result in unbalancing of the load, or that in removing the load-carrying platform from underneath the packages being carried thereon, the underside of the package may be damaged due to the contact between the edges of the load-carrying platform and the underside of the box. There is therefore a need for an easily operated unloading mechanism for use in connection with hand trucks which will remove packages on the hand truck from the load-carrying platform.
Several unloading devices have been proposed in the prior art, of which by far the most common tend to include an unloading shoe and a handle, the shoe connected to the bottom end of the handle and the handle pivotably connected to the upright frame of the hand truck. Of course, the problem with such an arrangement is that as the handle is pivoted, not only is the unloading shoe moved forward relative to the upright frame but also moves upward due to the pivoting action of the handle. This can damage packages, particularly cardboard boxes, which are being removed from the hand truck, due to the sliding contact between the unloading shoe and the side of the box.
Of course, others have tried to address this problem, including Olson, U.S. Pat. No. 5,290,051, and others. Olson, for example, provides a pivotal and slidable connection which includes a scissor link pivotally interconnecting the sideframe elements of the handle and corresponding upright elements of the hand truck frame, the scissor link causing the unloading shoe to move substantially horizontally across the load-carrying platform. Because of the scissor link construction of such devices, however, applications of large amounts of force to the handle, as would be done in removing a very heavy object from the hand truck, can result in failure of the unloading shoe subassembly. This is due to the fact that the scissor link design of the device pivots about a single pivot pin at all times, thus greatly increasing the wear and tear on the single pivot point. There is therefore a need for an unloading shoe subassembly which is sturdy in use and may be quickly and easily added to existing hand trucks.
Therefore, an object of the present invention is to provide an improved unloading shoe subassembly for use in connection with a hand truck.
Another object of the present invention is to provide an unloading shoe subassembly which may be quickly and easily added to existing hand trucks.
Another object of the present invention is to provide an unloading shoe subassembly in which the unloading shoe can be moved forwardly generally parallel with the load-carrying platform to unload packages from the hand truck without damaging the exterior of the packages.
Another object of the present invention is to provide an unloading shoe subassembly for a hand truck which is extremely sturdy in construction in order to allow the unloading shoe to remove relatively heavy objects from the load-carrying platform.
Another object of the present invention is to provide an unloading shoe subassembly for a hand truck which is spring-loaded to return the handle to an upright position substantially removed from interfering with the use of the hand truck in normal operation.
Another object of the present invention is to provide an unloading shoe subassembly for a hand truck, the subassembly including a pair of wheeled track assemblies for mounting on the hand truck frame, each of the wheeled track assemblies including upper, middle and lower tracks and wheels mounted within the tracks, the subassembly further including a shoe assembly having a shoe support strut, the shoe support strut pivotably attached to the wheels in the middle and lower tracks, and a handle for extending the shoe support shoe forwards is pivotably connected to the wheel in the upper track and one end of the shoe support strut.
Finally, an object of the present invention is to provide an unloading shoe subassembly which is relatively simple to manufacture, durable in construction and safe and efficient in use.